A liquid rubber dilution-resistant W / O emulsion plugging agent and its preparation method and application

Abstract

The present invention provides a liquid rubber dilution-resistant plugging W / O emulsion plugging agent and its preparation method and application, which belong to the technical field of high-temperature and high-salinity oil reservoir profile control and water blocking. The liquid rubber dilution-resistant plugging W / O emulsion plugging agent, calculated by mass, comprises the following raw materials: liquid rubber, oily solvent, 30-45 parts of formation water, 1-3 parts of calcium and magnesium ion complexing agent, 2-10 parts of polymer surfactant and 0.165-0.66 parts of high-temperature initiator; the liquid rubber and oily solvent are 55-70 parts in total. The emulsion plugging agent provided by the present invention is used for profile control and water blocking in high-temperature and high-salinity oil reservoirs to improve the water drive sweep efficiency, thereby improving the oil reservoir recovery rate. The emulsion plugging agent has excellent water scouring resistance. After being emulsified into gel in a simulated high-temperature and high-salinity oil reservoir environment, it can withstand temperatures of 150°C and salts of 22×10 4 mg / L, the W / O emulsion has good stability at high temperature and the gelling time of the emulsion plugging agent is controllable.

Description

Technical Field

[0001] The present invention relates to the technical field of profile control and water plugging in high-temperature and high-salinity oil reservoirs, and in particular to a liquid rubber dilution-resistant W / O emulsion plugging agent, a preparation method and application thereof. Background Art

[0002] As oilfields enter the high-water-cut development phase, due to formation heterogeneity and the formation of large pores from long-term scouring of injected water, dominant channels for injected water are formed in the formation, leading to coning, crossflow, and fingering, which seriously affect the water injection sweep coefficient and the economic benefits of oilfield development. Water plugging and profile control technology is one of the main technical means to improve the effectiveness of water injection development and achieve water control and oil stabilization. As the development of oil and gas fields deepens, the problem of water flooding in oilfields becomes increasingly complex. Plugging in the near-wellbore area cannot fundamentally solve the problem of low water flooding volume sweep coefficient. The research and development trend of plugging agents is gradually developing towards deep migration. Plugging agents are required to extend the gelling time under high temperature and high mineralization conditions, be able to migrate deep, and have long-term stable performance after gelling, thereby improving the recovery rate of oil and gas fields.

[0003] However, the crosslinking reaction time of various conventional profile control and water plugging agents in high-temperature, high-salinity reservoirs is difficult to control. Conventional free radical polymerization gelation takes too long to meet the profile control and water plugging requirements of deep reservoirs. Cross-linked polymer gels are currently the most widely used water plugging and profile control system, but their service temperature range is relatively narrow. Resin-based plugging agents have an applicable temperature range of 60-100°C. The process flow for these plugging agents is complex and the material cost is high. The matrix of oil-based plugging agents is typically composed of oily substances (such as hydrocarbons and fatty acid esters), which are immiscible with water. Therefore, they can be stable in the oil phase and, after injection into the reservoir, isolate themselves from water, reducing water penetration. However, the high cost of oil-based plugging agents and the high initial viscosity of the gelling solution make injection difficult. Controlling the viscosity and gelation time of plugging agents to ensure the blocking of high-permeability water flow channels in high-temperature, high-salinity reservoirs, control ineffective circulation, and improve reservoir recovery have become research hotspots. W / O emulsion polymers are formed by mixing an oil phase, an aqueous phase, and an emulsifier, resulting in an emulsion with an oil outer phase and a water inner phase. This emulsion exhibits a certain initial viscosity, ensuring it will not be flushed by formation water during injection. Furthermore, this emulsion system reduces the cost of oil-based systems. However, high-temperature, high-salinity reservoirs place extremely high demands on emulsion stability. Consequently, there is an urgent need to develop an emulsion plugging support system with excellent properties for high-temperature, high-salinity reservoirs, including high stability, controllable gelation time, temperature and salt tolerance, low cost, and resistance to water flushing. Summary of the Invention

[0004] In view of this, the present invention aims to provide a liquid rubber dilution-resistant W / O emulsion plugging agent and its preparation method and application. The liquid rubber dilution-resistant W / O emulsion plugging agent provided by the present invention is used for high-temperature and high-salinity oil reservoir profile control and water plugging to improve water flooding sweep efficiency, thereby improving oil reservoir recovery and achieving the purpose of stabilizing oil production and increasing oil field production. The emulsion plugging agent has excellent water scouring resistance. After emulsification into gel in a simulated high-temperature and high-salinity oil reservoir environment, it can withstand temperatures of 150°C and salts of 22×10 4 mg / L, the W / O emulsion has good stability at high temperatures, and the gelation time of the emulsion plugging agent is controllable. This emulsion-type water plugging agent has readily available raw materials, a simple and efficient preparation process, and proper cost control, which can meet the construction requirements of oilfield sites and has good practicality and economy.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is a liquid rubber dilution-resistant W / O emulsion plugging agent, which comprises, by weight, liquid rubber, an oily solvent, 30-45 parts of formation water, 1-3 parts of a calcium and magnesium ion complexing agent, 1-10 parts of a polymer surfactant, and 0.165-0.66 parts of a high-temperature initiator; the liquid rubber and the oily solvent together account for 55-70 parts, of which the liquid rubber accounts for 45%-55% of the total mass of the liquid rubber and the oily solvent.

[0007] A second technical solution of the present invention is a method for preparing the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent, comprising the following steps:

[0008] Mixing liquid rubber and oily solvent uniformly to obtain an oil phase;

[0009] dissolving a calcium and magnesium ion complexing agent in formation water to obtain an aqueous phase;

[0010] Adding a polymer surfactant to the oil phase, mixing uniformly, then adding the aqueous phase under stirring, mixing uniformly, to obtain a mixed solution;

[0011] The high-temperature initiator is uniformly dispersed in the mixed solution to obtain the liquid rubber dilution-resistant W / O emulsion plugging agent.

[0012] A third technical solution of the present invention is an application of the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent in fixed-point water plugging in deep layers of high-temperature and high-salinity oil reservoirs.

[0013] A fourth technical solution of the present invention is a method for fixed-point water plugging in deep layers of a high-temperature, high-salinity oil reservoir, which comprises injecting the above-mentioned liquid rubber dilution-resistant plugging W / O emulsion plugging agent into the high-temperature, high-salinity oil reservoir.

[0014] The present invention discloses the following technical effects:

[0015] By adding a calcium and magnesium ion complexing agent, the present invention allows calcium and magnesium ions in the aqueous phase to complex with the added calcium and magnesium ion complexing agent to form nanoparticle precipitation, which acts similarly to Pickering emulsification. The nanoparticles adsorb at the oil-water interface through electrostatic interactions and hydrogen bonding, forming a mechanical barrier that stabilizes the emulsion. This synergistic effect ensures that the liquid rubber dilution-resistant plugging emulsion system has excellent stability in high-temperature and high-salt oil reservoir environments.

[0016] The liquid rubber dilution-resistant plugging emulsion system provided by the present invention has the advantages of good injectability, excellent water scouring resistance, good emulsion system stability in high-temperature and high-salt environments, controllable gelation time, high gel mechanical strength and low cost. It has broad application prospects in profile control and water plugging in high-temperature and high-salt oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 The morphology of the liquid rubber dilution-resistant W / O emulsion plugging agent with different addition amounts of Arlacel P135 in Example 1 before (a) and after (b) gelation reaction in a simulated reservoir environment is shown;

[0019] Figure 2 FTIR image of the emulsion gel obtained by the liquid rubber dilution-resistant plugging W / O emulsion plugging agent in Example 6 when simulating the reservoir environment;

[0020] Figure 3 The graphs show the rheological properties of the emulsion gel obtained from the liquid rubber dilution-resistant W / O emulsion plugging agent in Example 6 in a simulated reservoir environment, where (a) is a strain sweep (0.1% to 1000%) and (b) is a frequency sweep (0.1 to 15 Hz).

[0021] Figure 4 These are test diagrams of the water dilution resistance of the liquid rubber dilution-resistant W / O emulsion plugging agent in Example 6, wherein (a) shows a drop of liquid rubber dilution-resistant W / O emulsion plugging agent dripped into formation water, (b) shows a glass bottle filled with some formation water and some liquid rubber dilution-resistant W / O emulsion plugging agent, and (c) shows the liquid rubber dilution-resistant W / O emulsion plugging agent after gelling.

[0022] Figure 5The morphology of the emulsion gel formed by the liquid rubber dilution-resistant W / O emulsion plugging agent in Examples 4, 5, and 6 in a simulated reservoir environment is shown before the plugging agent reaction (a), after the reaction (b), and at a 1.0 wt% addition (c);

[0023] Figure 6 It is the Sydansk gel strength code method;

[0024] Figure 7 Schematic diagram of the cross-linking mechanism of liquid rubber dilution-resistant W / O emulsion plugging agent. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] The mass fractions described in the following embodiments may be grams, kilograms, tons or other mass units.

[0031] The first aspect of the present invention provides a liquid rubber dilution-resistant W / O emulsion plugging agent, which comprises, by weight, liquid rubber, an oily solvent, 30-45 parts of formation water, 1-3 parts of a calcium and magnesium ion complexing agent, 1-10 parts of a polymeric surfactant, and 0.165-0.66 parts of a high-temperature initiator; the liquid rubber and the oily solvent together account for 55-70 parts, wherein the liquid rubber accounts for 45%-55% of the total mass of the liquid rubber and the oily solvent.

[0032] In the present invention, the liquid rubber is liquid polybutadiene; the oily solvent is kerosene and / or 3# white oil, preferably 3# white oil.

[0033] Formation water, also known as oil layer water, refers to the edge water and bottom water at the edge and bottom of the oil reservoir, interlayer water, and bound water in the same layer as the crude oil. In the present invention, in order to simulate the composition of formation water, laboratory preparation was carried out. The content composition of simulated formation water is shown in Table 1.

[0034] Table 1 Content composition of simulated formation water

[0035]

[0036] In some embodiments of the present invention, the calcium and magnesium ion complexing agent is sodium bicarbonate, sodium oxalate, sodium citrate, sodium aluminate or sodium hydroxide.

[0037] In some embodiments of the present invention, the polymer surfactant is polyethylene glycol (30) dipolyhydroxystearate (Arlacel P135), polyether polyol or Span80, preferably Arlacel P135.

[0038] In some embodiments of the present invention, the high-temperature initiator is tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide or tert-butyl perbenzoate, preferably tert-butyl perbenzoate.

[0039] The two large, long chains of the polymeric surfactant used in this invention form a non-rotating, three-dimensional structure at the emulsion interface. These structures are irreversibly adsorbed at the oil-water interface, forming a strong, highly elastic interfacial membrane. The addition of a calcium and magnesium ion complexing agent allows for complexation with calcium and magnesium ions in the formation water to generate solid particles that adsorb at the oil-water interface, forming a strong physical barrier and maintaining the emulsion's stability. The synergistic effect of the polymeric surfactant and the solid particles ensures the liquid rubber W / O emulsion's excellent stability in high-temperature, high-salinity reservoirs, effectively sealing areas where water is produced.

[0040] A second aspect of the present invention provides a method for preparing the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent, comprising the following steps:

[0041] Mixing liquid rubber and oily solvent uniformly to obtain an oil phase;

[0042] dissolving a calcium and magnesium ion complexing agent in formation water to obtain an aqueous phase;

[0043] Adding a polymer surfactant to the oil phase, mixing uniformly, then adding the aqueous phase under stirring, mixing uniformly, to obtain a mixed solution;

[0044] The high-temperature initiator is uniformly dispersed in the mixed solution to obtain the liquid rubber dilution-resistant W / O emulsion plugging agent.

[0045] The present invention does not impose any particular limitation on the manner of uniform mixing, dissolving and dispersing, and any technical means well known to those skilled in the art may be used, such as stirring.

[0046] A third aspect of the present invention provides an application of the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent in fixed-point water plugging in deep layers of high-temperature and high-salinity oil reservoirs.

[0047] A fourth aspect of the present invention provides a method for deep-layer fixed-point water plugging in a high-temperature, high-salinity oil reservoir, wherein the liquid rubber dilution-resistant W / O emulsion plugging agent is injected into the high-temperature, high-salinity oil reservoir.

[0048] After the liquid rubber dilution-resistant W / O emulsion plugging agent (i.e., plugging agent) is injected into a high-temperature and high-salt oil reservoir, the plugging agent gradually migrates to the deep layer, forms a gel in the high-temperature and high-pressure environment deep in the oil reservoir, and completes the profile control and water plugging of the deep oil reservoir.

[0049] Unless otherwise specified, the technical solutions described in the present invention are all conventional solutions in the field, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0050] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0051] The formation water in the examples is laboratory simulated formation water, and the content composition of the simulated formation water is shown in Table 1.

[0052] Example 1

[0053] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0054] (1) Weigh 30 parts of liquid polybutadiene and 30 parts of 3# white oil, stir them on a magnetic stirrer for 15 minutes to mix them evenly, and obtain an oil phase;

[0055] (2) Weigh 40 parts of formation water, then add 1.2 parts of NaOH to the formation water and stir for 15 minutes to fully dissolve the NaOH in the formation water to obtain an aqueous phase;

[0056] (3) Adding Arlacel P135 (the amounts of Arlacel P135 were 1.2 parts, 2.4 parts, 3.6 parts, 4.8 parts, and 6 parts, respectively) to the oil phase prepared in step (1) and stirring for 15 minutes to fully mix with the oil phase. Then, adding the above-prepared aqueous phase under stirring and stirring with a magnetic stirrer for 30 minutes to fully mix, to obtain a mixed solution;

[0057] (4) 0.6 parts of tert-butyl perbenzoate are dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent).

[0058] The performance of the plugging agent was tested by simulating the actual environment in which the plugging agent is used in the reservoir. The plugging agent was placed in a high-temperature and high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent the aqueous phase from evaporating at high temperatures. The reaction was then carried out in a 150°C forced air drying oven at simulated reservoir temperature for 8 hours. The emulsion gel formed before and after the reaction is as follows: Figure 1 (In the figure, 2wt% indicates that the amount of Arlacel P135 is 1.2 parts, and the mass ratio of Arlacel P135 to the oil phase is 2wt%; 4wt% indicates that the amount of Arlacel P135 is 2.4 parts, and the mass ratio of Arlacel P135 to the oil phase is 4wt%; 6wt% indicates that the amount of Arlacel P135 is 3.6 parts, and the mass ratio of Arlacel P135 to the oil phase is 6wt%; 8wt% indicates that the amount of Arlacel P135 is 4.8 parts, and the mass ratio of Arlacel P135 to the oil phase is 8wt%; 10wt% indicates that the amount of Arlacel P135 is 6.0 parts, and the mass ratio of Arlacel P135 to the oil phase is 10wt%). It can be seen that the strength grade of the emulsion gel after gelation at a high temperature of 150°C is all Class I.

[0059] Example 2

[0060] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0061] (1) Weigh 27 parts of liquid polybutadiene and 33 parts of No. 3 white oil, stir them on a magnetic stirrer for 15 minutes to mix them evenly, and obtain an oil phase;

[0062] (2) Weigh 40 parts of formation water, then add 1.2 parts of NaOH to the formation water and stir for 15 minutes to fully dissolve the NaOH in the formation water to obtain an aqueous phase;

[0063] (3) Add 3.6 parts of Arlacel P135 (i.e., Arlacel P135 accounts for 6% of the mass of the oil phase) to the oil phase prepared in step (1) and stir for 15 minutes to fully mix with the oil phase. Then, add the above-prepared aqueous phase while stirring and stir with a magnetic stirrer for 30 minutes to fully mix to obtain a mixed solution;

[0064] (4) 0.405 parts of tert-butyl perbenzoate are dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent).

[0065] The performance of the plugging control agent was tested to simulate the actual reservoir application environment. The agent was placed in a high-temperature, high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent evaporation of the aqueous phase at high temperatures. The mixture was then reacted in a 150°C forced air drying oven for 8 hours at simulated reservoir temperatures. The resulting emulsion gels, formed at 150°C, all demonstrated a strength rating of Class I.

[0066] Example 3

[0067] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0068] (1) Weigh 33 parts of liquid polybutadiene and 27 parts of 3# white oil, stir them on a magnetic stirrer for 15 minutes to mix them evenly, and obtain an oil phase;

[0069] (2) Weigh 40 parts of formation water, then add 1.2 parts of NaOH to the formation water and stir for 15 minutes to fully dissolve the NaOH in the formation water to obtain an aqueous phase;

[0070] (3) Add 3.6 parts of Arlacel P135 (i.e., Arlacel P135 accounts for 6% of the mass of the oil phase) to the oil phase prepared in step (1) and stir for 15 minutes to fully mix with the oil phase. Then, add the above-prepared aqueous phase while stirring and stir with a magnetic stirrer for 30 minutes to fully mix to obtain a mixed solution;

[0071] (4) 0.495 parts of tert-butyl perbenzoate are dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent).

[0072] The performance of the plugging control agent was tested to simulate the actual reservoir application environment. The agent was placed in a high-temperature, high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent evaporation of the aqueous phase at high temperatures. The mixture was then reacted in a 150°C forced air drying oven for 8 hours at simulated reservoir temperatures. The resulting emulsion gels, formed at 150°C, all demonstrated a strength rating of Class I.

[0073] Example 4

[0074] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0075] (1) Weigh 27.5 parts of liquid polybutadiene and 27.5 parts of 3# white oil, stir them on a magnetic stirrer for 15 minutes to mix them evenly, and obtain an oil phase;

[0076] (2) Weigh 45 parts of formation water, then add 1.35 parts of NaOH to the formation water and stir for 15 minutes to fully dissolve the NaOH in the formation water to obtain an aqueous phase;

[0077] (3) Add 3.3 parts of Arlacel P135 (i.e., Arlacel P135 accounts for 6% of the mass of the oil phase) to the oil phase prepared in step (1) and stir for 15 minutes to fully mix with the oil phase. Then, add the above-prepared aqueous phase while stirring and stir with a magnetic stirrer for 30 minutes to fully mix to obtain a mixed solution;

[0078] (4) 0.1375 parts of tert-butyl peroxybenzoate were dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent). The amount of high-temperature initiator used in this embodiment is lower than that of the comparative example of 0.165-0.66 parts.

[0079] The performance of the plugging control agent was tested to simulate the actual reservoir application environment. The agent was placed in a high-temperature, high-pressure reactor and pressurized with nitrogen to 2.0 MPa to prevent evaporation of the dispersed aqueous phase at high temperatures. The mixture was then reacted in a 150°C forced air drying oven at simulated reservoir temperatures. After 15 hours at 150°C, no gel formed. This suggests that if the amount of high-temperature initiator used is too low, the resulting emulsion plugging agent will have difficulty reacting at high temperatures.

[0080] Example 5

[0081] Same as Example 4, except that 0.275 parts of tert-butyl perbenzoate is added in step (4).

[0082] The performance of the plugging control agent was tested to simulate the actual reservoir application environment. The agent was placed in a high-temperature, high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent evaporation of the aqueous phase at high temperatures. The reaction was then carried out in a 150°C forced air drying oven for 13 hours at simulated reservoir temperatures. The resulting emulsion gels, gelled at 150°C, all demonstrated a strength rating of Class I.

[0083] Example 6

[0084] Same as Example 4, except that 0.4125 parts of tert-butyl perbenzoate is added in step (4).

[0085] The performance of the plugging control agent was tested to simulate the actual reservoir application environment. The agent was placed in a high-temperature, high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent evaporation of the aqueous phase at high temperatures. The mixture was then reacted in a 150°C forced air drying oven for 8 hours at simulated reservoir temperatures. The resulting emulsion gels, formed at 150°C, all demonstrated a strength rating of Class I.

[0086] The infrared characterization test of the plugging agent obtained in this embodiment was carried out ( Figure 2 ) and rheological properties tests ( Figure 3 ), and its water erosion resistance was evaluated. Figure 4 As shown. The rheological test results show that the elastic modulus (G′) of the formed emulsion gel is about 2000Pa, and the viscous modulus (G″) is about 260Pa, which shows that the plugging agent has excellent mechanical properties. This property enables the gel to effectively seal cracks in the formation. In this way, it can improve the fluid conductivity efficiency during oil and gas production, thereby increasing the recovery rate. In the evaluation of water dilution resistance, it can be found that after a drop of emulsion is dropped into the formation water, it can remain stable for a long time without demulsification. After pouring part of the formation water and part of the emulsion into the glass bottle, the emulsion remained uniform and did not demulsify after gelation, indicating that the emulsion system has excellent water dilution resistance.

[0087] Depend on Figure 5 (In the figure, wt% is calculated from the mass ratio of tert-butyl perbenzoate and liquid polybutadiene, 0.5wt% represents Example 4, 1wt% represents Example 5, and 1.5wt% represents Example 6) It can be seen that the gelation time is different depending on the amount of high-temperature initiator used. The present invention can control the gelation time by controlling the amount of high-temperature initiator used.

[0088] Example 7

[0089] The same as Example 2, except that 3.6 parts of a polyether polyol was added to the oil phase as the polymer surfactant. The prepared liquid rubber, dilution-resistant W / O emulsion plugging agent was subjected to gelation experiments in a simulated reservoir environment. After reacting at 150°C for 8 hours, the resulting emulsion gel partially demulsified, resulting in a gel strength of Class H.

[0090] Example 8

[0091] The same as Example 2, except that 3.6 parts of Span 80 was added to the oil phase as the polymer surfactant. The prepared liquid rubber dilution-resistant W / O emulsion plugging agent was subjected to gelation experiments in a simulated reservoir environment. After reacting at 150°C for 8 hours, the resulting emulsion gel partially demulsified, resulting in a G-grade gel strength.

[0092] From Examples 2, 7, and 8, it can be seen that the stability of Arlacel P135 emulsifier at high temperatures is better than that of polyether polyol and Span80. Arlacel P135 has stronger thermal stability and anti-demulsification ability at high temperatures and is more suitable for use in high-temperature and high-salinity oil reservoirs. All gel strengths in this invention are evaluated using the Sydansk gel strength code method, such as Figure 6 The cross-linking mechanism of liquid rubber dilution-resistant W / O emulsion plugging agent is shown in the figure. Figure 7 shown.

[0093] In summary, the preparation process of the liquid rubber dilution-resistant W / O emulsion plugging agent of the present invention is simpler, low-cost, and the gelation time under high temperature and high salinity is controllable. It has excellent water dilution resistance and stability, can effectively improve the water flooding sweep efficiency, and thus improve the oil reservoir recovery rate.

[0094] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A liquid rubber dilution-resistant W / O emulsion plugging agent, characterized in that: The raw materials include, by weight, liquid rubber, an oily solvent, 30-45 parts of formation water, 1-3 parts of a calcium and magnesium ion complexing agent, 1-10 parts of a polymer surfactant, and 0.165-0.66 parts of a high-temperature initiator; the liquid rubber and the oily solvent together account for 55-70 parts, of which the liquid rubber accounts for 45%-55% of the total weight of the liquid rubber and the oily solvent; The liquid rubber is liquid polybutadiene; the oily solvent is kerosene and / or 3# white oil; The calcium and magnesium ion complexing agent is sodium bicarbonate, sodium oxalate, sodium citrate, sodium aluminate or sodium hydroxide; The polymer surfactant is polyethylene glycol (30) dipolyhydroxystearate, polyether polyol or Span80; The high-temperature initiator is tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide or tert-butyl perbenzoate.

2. A method for preparing the liquid rubber dilution-resistant W / O emulsion plugging agent according to claim 1, characterized in that: The following steps are involved: Mixing liquid rubber and oily solvent uniformly to obtain an oil phase; dissolving a calcium and magnesium ion complexing agent in formation water to obtain an aqueous phase; Adding a polymer surfactant to the oil phase, mixing uniformly, then adding the aqueous phase under stirring, mixing uniformly, to obtain a mixed solution; The high-temperature initiator is uniformly dispersed in the mixed solution to obtain the liquid rubber dilution-resistant W / O emulsion plugging agent.

3. Use of the liquid rubber dilution-resistant W / O emulsion plugging agent according to claim 1 in deep-layer fixed-point water plugging in high-temperature and high-salinity oil reservoirs.

4. A method for fixed-point water plugging in deep layers of high-temperature and high-salinity oil reservoirs, characterized in that: The liquid rubber dilution-resistant W / O emulsion plugging agent according to claim 1 is injected into a high-temperature and high-salt oil reservoir.

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